Earth working box blade implements commonly form a partially enclosed rigid box frame which includes left and right sidewalls and an earth screeding or scraping blade which spans laterally between such walls. Such implements are commonly pulled by forwardly extending towing tongue behind a tractor. Alternatively, box blades are known to be mounted to the rear of a tractor upon the tractor's three point hitch arms. Further alternatively, box blades graders may be adapted for attachment to the lift arms of a front end loader or skid steer loader vehicle.
Such conventional box blade earth grading implements commonly lack any capability or capacity for raising and lowering the blade in relation to ground level. Also, they commonly lack any capability of adjusting the angle or lateral tilt of the blade with respect to the level of a ground surface to be graded. In the event that such conventional box blade implements encounter or are driven against a protrusion such as a rock, the box blade commonly becomes undesirably laterally tilted, temporarily interrupting and interfering with the smooth progress of earth grading.
The instant inventive box blade earth grading implement solves or ameliorates the problems, defects, and challenges of conventional box blades discussed above by specially configuring the box's left and right walls to include extendable and retractable segments, by applying linear motion actuators to effect such extensions and retractions, and by associating pivot joints with the each of the walls' lower segments.